Applicable Systems
Greenstar GB162
Symptoms
The Worcester Bosch Greenstar Ri ErP boiler displays a low system pressure indication. The boiler has detected that the central heating system water pressure has dropped below the minimum safe operating pressure of 1.0 bar.
Possible Causes
- Water leak in the heating system (radiator valves, pipe joints, or boiler internals)
- System pressure not recharged after recent radiator bleeding or maintenance
- Expansion vessel lost its air charge or diaphragm ruptured
- Pressure relief valve passing water to the discharge pipe
Troubleshooting Steps
- Step 1: Check the boiler pressure gauge reading
Pressure should be 1.0-1.5 bar when cold; if below 1.0 bar, the system needs repressurizing - Step 2: Repressurize the system using the external filling loop
Open both valves on the filling loop slowly until pressure reaches 1.2-1.5 bar, then close both valves - Step 3: Inspect all visible pipework and radiator valves for water leaks
Look for water stains, green corrosion on copper, or dripping at valve connections - Step 4: Check the pressure relief valve discharge pipe outside for water
If water is dripping from the copper discharge pipe, the PRV needs replacement
How to Reset
To reset: 1) Repressurize the system to 1.2-1.5 bar using the filling loop. 2) The boiler should restart automatically once pressure is restored. 3) If pressure drops again within hours, there is a system leak that must be found and repaired. Caution: Operating a boiler with low pressure can cause the pump to run dry and the heat exchanger to overheat.
Frequently Asked Questions
- Q: How often should I need to repressurize my Worcester Bosch boiler?
A properly sealed system should maintain pressure for months. If you need to repressurize more than once every few months, there is likely a leak in the system that needs professional attention.
- Q: What if the pressure drops immediately after repressurizing?
If pressure drops immediately after filling, you have a significant leak. Check visible pipework and radiator valves first. If no visible leak is found, the leak may be under floors or in the boiler internals - contact a Gas Safe engineer.
Source: Worcester Bosch Greenstar Ri ErP Installation and Servicing Instructions, Fault Finding Section, Document 6720813340
Category: Home Boiler